2 * trace irqs off critical timings
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 * From code in the latency_tracer, that is:
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 William Lee Irwin III
12 #include <linux/kallsyms.h>
13 #include <linux/debugfs.h>
14 #include <linux/uaccess.h>
15 #include <linux/module.h>
16 #include <linux/ftrace.h>
21 static struct trace_array
*irqsoff_trace __read_mostly
;
22 static int tracer_enabled __read_mostly
;
24 static DEFINE_PER_CPU(int, tracing_cpu
);
26 static DEFINE_RAW_SPINLOCK(max_trace_lock
);
29 TRACER_IRQS_OFF
= (1 << 1),
30 TRACER_PREEMPT_OFF
= (1 << 2),
33 static int trace_type __read_mostly
;
35 static int save_lat_flag
;
37 static void stop_irqsoff_tracer(struct trace_array
*tr
, int graph
);
38 static int start_irqsoff_tracer(struct trace_array
*tr
, int graph
);
40 #ifdef CONFIG_PREEMPT_TRACER
44 return ((trace_type
& TRACER_PREEMPT_OFF
) && preempt_count());
47 # define preempt_trace() (0)
50 #ifdef CONFIG_IRQSOFF_TRACER
54 return ((trace_type
& TRACER_IRQS_OFF
) &&
58 # define irq_trace() (0)
61 #define TRACE_DISPLAY_GRAPH 1
63 static struct tracer_opt trace_opts
[] = {
64 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
65 /* display latency trace as call graph */
66 { TRACER_OPT(display
-graph
, TRACE_DISPLAY_GRAPH
) },
71 static struct tracer_flags tracer_flags
= {
76 #define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
79 * Sequence count - we record it when starting a measurement and
80 * skip the latency if the sequence has changed - some other section
81 * did a maximum and could disturb our measurement with serial console
82 * printouts, etc. Truly coinciding maximum latencies should be rare
83 * and what happens together happens separately as well, so this doesn't
84 * decrease the validity of the maximum found:
86 static __cacheline_aligned_in_smp
unsigned long max_sequence
;
88 #ifdef CONFIG_FUNCTION_TRACER
90 * Prologue for the preempt and irqs off function tracers.
92 * Returns 1 if it is OK to continue, and data->disabled is
94 * 0 if the trace is to be ignored, and data->disabled
97 * Note, this function is also used outside this ifdef but
98 * inside the #ifdef of the function graph tracer below.
99 * This is OK, since the function graph tracer is
100 * dependent on the function tracer.
102 static int func_prolog_dec(struct trace_array
*tr
,
103 struct trace_array_cpu
**data
,
104 unsigned long *flags
)
110 * Does not matter if we preempt. We test the flags
111 * afterward, to see if irqs are disabled or not.
112 * If we preempt and get a false positive, the flags
115 cpu
= raw_smp_processor_id();
116 if (likely(!per_cpu(tracing_cpu
, cpu
)))
119 local_save_flags(*flags
);
120 /* slight chance to get a false positive on tracing_cpu */
121 if (!irqs_disabled_flags(*flags
))
124 *data
= tr
->data
[cpu
];
125 disabled
= atomic_inc_return(&(*data
)->disabled
);
127 if (likely(disabled
== 1))
130 atomic_dec(&(*data
)->disabled
);
136 * irqsoff uses its own tracer function to keep the overhead down:
139 irqsoff_tracer_call(unsigned long ip
, unsigned long parent_ip
,
140 struct ftrace_ops
*op
, struct pt_regs
*pt_regs
)
142 struct trace_array
*tr
= irqsoff_trace
;
143 struct trace_array_cpu
*data
;
146 if (!func_prolog_dec(tr
, &data
, &flags
))
149 trace_function(tr
, ip
, parent_ip
, flags
, preempt_count());
151 atomic_dec(&data
->disabled
);
154 static struct ftrace_ops trace_ops __read_mostly
=
156 .func
= irqsoff_tracer_call
,
157 .flags
= FTRACE_OPS_FL_GLOBAL
| FTRACE_OPS_FL_RECURSION_SAFE
,
159 #endif /* CONFIG_FUNCTION_TRACER */
161 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
162 static int irqsoff_set_flag(u32 old_flags
, u32 bit
, int set
)
166 if (!(bit
& TRACE_DISPLAY_GRAPH
))
169 if (!(is_graph() ^ set
))
172 stop_irqsoff_tracer(irqsoff_trace
, !set
);
174 for_each_possible_cpu(cpu
)
175 per_cpu(tracing_cpu
, cpu
) = 0;
177 tracing_max_latency
= 0;
178 tracing_reset_online_cpus(irqsoff_trace
);
180 return start_irqsoff_tracer(irqsoff_trace
, set
);
183 static int irqsoff_graph_entry(struct ftrace_graph_ent
*trace
)
185 struct trace_array
*tr
= irqsoff_trace
;
186 struct trace_array_cpu
*data
;
191 if (!func_prolog_dec(tr
, &data
, &flags
))
194 pc
= preempt_count();
195 ret
= __trace_graph_entry(tr
, trace
, flags
, pc
);
196 atomic_dec(&data
->disabled
);
201 static void irqsoff_graph_return(struct ftrace_graph_ret
*trace
)
203 struct trace_array
*tr
= irqsoff_trace
;
204 struct trace_array_cpu
*data
;
208 if (!func_prolog_dec(tr
, &data
, &flags
))
211 pc
= preempt_count();
212 __trace_graph_return(tr
, trace
, flags
, pc
);
213 atomic_dec(&data
->disabled
);
216 static void irqsoff_trace_open(struct trace_iterator
*iter
)
219 graph_trace_open(iter
);
223 static void irqsoff_trace_close(struct trace_iterator
*iter
)
226 graph_trace_close(iter
);
229 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
230 TRACE_GRAPH_PRINT_PROC | \
231 TRACE_GRAPH_PRINT_ABS_TIME | \
232 TRACE_GRAPH_PRINT_DURATION)
234 static enum print_line_t
irqsoff_print_line(struct trace_iterator
*iter
)
237 * In graph mode call the graph tracer output function,
238 * otherwise go with the TRACE_FN event handler
241 return print_graph_function_flags(iter
, GRAPH_TRACER_FLAGS
);
243 return TRACE_TYPE_UNHANDLED
;
246 static void irqsoff_print_header(struct seq_file
*s
)
249 print_graph_headers_flags(s
, GRAPH_TRACER_FLAGS
);
251 trace_default_header(s
);
255 __trace_function(struct trace_array
*tr
,
256 unsigned long ip
, unsigned long parent_ip
,
257 unsigned long flags
, int pc
)
260 trace_graph_function(tr
, ip
, parent_ip
, flags
, pc
);
262 trace_function(tr
, ip
, parent_ip
, flags
, pc
);
266 #define __trace_function trace_function
268 static int irqsoff_set_flag(u32 old_flags
, u32 bit
, int set
)
273 static int irqsoff_graph_entry(struct ftrace_graph_ent
*trace
)
278 static enum print_line_t
irqsoff_print_line(struct trace_iterator
*iter
)
280 return TRACE_TYPE_UNHANDLED
;
283 static void irqsoff_graph_return(struct ftrace_graph_ret
*trace
) { }
284 static void irqsoff_trace_open(struct trace_iterator
*iter
) { }
285 static void irqsoff_trace_close(struct trace_iterator
*iter
) { }
287 #ifdef CONFIG_FUNCTION_TRACER
288 static void irqsoff_print_header(struct seq_file
*s
)
290 trace_default_header(s
);
293 static void irqsoff_print_header(struct seq_file
*s
)
295 trace_latency_header(s
);
297 #endif /* CONFIG_FUNCTION_TRACER */
298 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
301 * Should this new latency be reported/recorded?
303 static int report_latency(cycle_t delta
)
305 if (tracing_thresh
) {
306 if (delta
< tracing_thresh
)
309 if (delta
<= tracing_max_latency
)
316 check_critical_timing(struct trace_array
*tr
,
317 struct trace_array_cpu
*data
,
318 unsigned long parent_ip
,
321 cycle_t T0
, T1
, delta
;
325 T0
= data
->preempt_timestamp
;
326 T1
= ftrace_now(cpu
);
329 local_save_flags(flags
);
331 pc
= preempt_count();
333 if (!report_latency(delta
))
336 raw_spin_lock_irqsave(&max_trace_lock
, flags
);
338 /* check if we are still the max latency */
339 if (!report_latency(delta
))
342 __trace_function(tr
, CALLER_ADDR0
, parent_ip
, flags
, pc
);
343 /* Skip 5 functions to get to the irq/preempt enable function */
344 __trace_stack(tr
, flags
, 5, pc
);
346 if (data
->critical_sequence
!= max_sequence
)
349 data
->critical_end
= parent_ip
;
351 if (likely(!is_tracing_stopped())) {
352 tracing_max_latency
= delta
;
353 update_max_tr_single(tr
, current
, cpu
);
359 raw_spin_unlock_irqrestore(&max_trace_lock
, flags
);
362 data
->critical_sequence
= max_sequence
;
363 data
->preempt_timestamp
= ftrace_now(cpu
);
364 __trace_function(tr
, CALLER_ADDR0
, parent_ip
, flags
, pc
);
368 start_critical_timing(unsigned long ip
, unsigned long parent_ip
)
371 struct trace_array
*tr
= irqsoff_trace
;
372 struct trace_array_cpu
*data
;
375 if (likely(!tracer_enabled
))
378 cpu
= raw_smp_processor_id();
380 if (per_cpu(tracing_cpu
, cpu
))
383 data
= tr
->data
[cpu
];
385 if (unlikely(!data
) || atomic_read(&data
->disabled
))
388 atomic_inc(&data
->disabled
);
390 data
->critical_sequence
= max_sequence
;
391 data
->preempt_timestamp
= ftrace_now(cpu
);
392 data
->critical_start
= parent_ip
? : ip
;
394 local_save_flags(flags
);
396 __trace_function(tr
, ip
, parent_ip
, flags
, preempt_count());
398 per_cpu(tracing_cpu
, cpu
) = 1;
400 atomic_dec(&data
->disabled
);
404 stop_critical_timing(unsigned long ip
, unsigned long parent_ip
)
407 struct trace_array
*tr
= irqsoff_trace
;
408 struct trace_array_cpu
*data
;
411 cpu
= raw_smp_processor_id();
412 /* Always clear the tracing cpu on stopping the trace */
413 if (unlikely(per_cpu(tracing_cpu
, cpu
)))
414 per_cpu(tracing_cpu
, cpu
) = 0;
421 data
= tr
->data
[cpu
];
423 if (unlikely(!data
) ||
424 !data
->critical_start
|| atomic_read(&data
->disabled
))
427 atomic_inc(&data
->disabled
);
429 local_save_flags(flags
);
430 __trace_function(tr
, ip
, parent_ip
, flags
, preempt_count());
431 check_critical_timing(tr
, data
, parent_ip
? : ip
, cpu
);
432 data
->critical_start
= 0;
433 atomic_dec(&data
->disabled
);
436 /* start and stop critical timings used to for stoppage (in idle) */
437 void start_critical_timings(void)
439 if (preempt_trace() || irq_trace())
440 start_critical_timing(CALLER_ADDR0
, CALLER_ADDR1
);
442 EXPORT_SYMBOL_GPL(start_critical_timings
);
444 void stop_critical_timings(void)
446 if (preempt_trace() || irq_trace())
447 stop_critical_timing(CALLER_ADDR0
, CALLER_ADDR1
);
449 EXPORT_SYMBOL_GPL(stop_critical_timings
);
451 #ifdef CONFIG_IRQSOFF_TRACER
452 #ifdef CONFIG_PROVE_LOCKING
453 void time_hardirqs_on(unsigned long a0
, unsigned long a1
)
455 if (!preempt_trace() && irq_trace())
456 stop_critical_timing(a0
, a1
);
459 void time_hardirqs_off(unsigned long a0
, unsigned long a1
)
461 if (!preempt_trace() && irq_trace())
462 start_critical_timing(a0
, a1
);
465 #else /* !CONFIG_PROVE_LOCKING */
471 void trace_softirqs_on(unsigned long ip
)
475 void trace_softirqs_off(unsigned long ip
)
479 inline void print_irqtrace_events(struct task_struct
*curr
)
484 * We are only interested in hardirq on/off events:
486 void trace_hardirqs_on(void)
488 if (!preempt_trace() && irq_trace())
489 stop_critical_timing(CALLER_ADDR0
, CALLER_ADDR1
);
491 EXPORT_SYMBOL(trace_hardirqs_on
);
493 void trace_hardirqs_off(void)
495 if (!preempt_trace() && irq_trace())
496 start_critical_timing(CALLER_ADDR0
, CALLER_ADDR1
);
498 EXPORT_SYMBOL(trace_hardirqs_off
);
500 void trace_hardirqs_on_caller(unsigned long caller_addr
)
502 if (!preempt_trace() && irq_trace())
503 stop_critical_timing(CALLER_ADDR0
, caller_addr
);
505 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
507 void trace_hardirqs_off_caller(unsigned long caller_addr
)
509 if (!preempt_trace() && irq_trace())
510 start_critical_timing(CALLER_ADDR0
, caller_addr
);
512 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
514 #endif /* CONFIG_PROVE_LOCKING */
515 #endif /* CONFIG_IRQSOFF_TRACER */
517 #ifdef CONFIG_PREEMPT_TRACER
518 void trace_preempt_on(unsigned long a0
, unsigned long a1
)
520 if (preempt_trace() && !irq_trace())
521 stop_critical_timing(a0
, a1
);
524 void trace_preempt_off(unsigned long a0
, unsigned long a1
)
526 if (preempt_trace() && !irq_trace())
527 start_critical_timing(a0
, a1
);
529 #endif /* CONFIG_PREEMPT_TRACER */
531 static int start_irqsoff_tracer(struct trace_array
*tr
, int graph
)
536 ret
= register_ftrace_function(&trace_ops
);
538 ret
= register_ftrace_graph(&irqsoff_graph_return
,
539 &irqsoff_graph_entry
);
541 if (!ret
&& tracing_is_enabled())
549 static void stop_irqsoff_tracer(struct trace_array
*tr
, int graph
)
554 unregister_ftrace_function(&trace_ops
);
556 unregister_ftrace_graph();
559 static void __irqsoff_tracer_init(struct trace_array
*tr
)
561 save_lat_flag
= trace_flags
& TRACE_ITER_LATENCY_FMT
;
562 trace_flags
|= TRACE_ITER_LATENCY_FMT
;
564 tracing_max_latency
= 0;
566 /* make sure that the tracer is visible */
568 tracing_reset_online_cpus(tr
);
570 if (start_irqsoff_tracer(tr
, is_graph()))
571 printk(KERN_ERR
"failed to start irqsoff tracer\n");
574 static void irqsoff_tracer_reset(struct trace_array
*tr
)
576 stop_irqsoff_tracer(tr
, is_graph());
579 trace_flags
&= ~TRACE_ITER_LATENCY_FMT
;
582 static void irqsoff_tracer_start(struct trace_array
*tr
)
587 static void irqsoff_tracer_stop(struct trace_array
*tr
)
592 #ifdef CONFIG_IRQSOFF_TRACER
593 static int irqsoff_tracer_init(struct trace_array
*tr
)
595 trace_type
= TRACER_IRQS_OFF
;
597 __irqsoff_tracer_init(tr
);
600 static struct tracer irqsoff_tracer __read_mostly
=
603 .init
= irqsoff_tracer_init
,
604 .reset
= irqsoff_tracer_reset
,
605 .start
= irqsoff_tracer_start
,
606 .stop
= irqsoff_tracer_stop
,
608 .print_header
= irqsoff_print_header
,
609 .print_line
= irqsoff_print_line
,
610 .flags
= &tracer_flags
,
611 .set_flag
= irqsoff_set_flag
,
612 #ifdef CONFIG_FTRACE_SELFTEST
613 .selftest
= trace_selftest_startup_irqsoff
,
615 .open
= irqsoff_trace_open
,
616 .close
= irqsoff_trace_close
,
619 # define register_irqsoff(trace) register_tracer(&trace)
621 # define register_irqsoff(trace) do { } while (0)
624 #ifdef CONFIG_PREEMPT_TRACER
625 static int preemptoff_tracer_init(struct trace_array
*tr
)
627 trace_type
= TRACER_PREEMPT_OFF
;
629 __irqsoff_tracer_init(tr
);
633 static struct tracer preemptoff_tracer __read_mostly
=
635 .name
= "preemptoff",
636 .init
= preemptoff_tracer_init
,
637 .reset
= irqsoff_tracer_reset
,
638 .start
= irqsoff_tracer_start
,
639 .stop
= irqsoff_tracer_stop
,
641 .print_header
= irqsoff_print_header
,
642 .print_line
= irqsoff_print_line
,
643 .flags
= &tracer_flags
,
644 .set_flag
= irqsoff_set_flag
,
645 #ifdef CONFIG_FTRACE_SELFTEST
646 .selftest
= trace_selftest_startup_preemptoff
,
648 .open
= irqsoff_trace_open
,
649 .close
= irqsoff_trace_close
,
652 # define register_preemptoff(trace) register_tracer(&trace)
654 # define register_preemptoff(trace) do { } while (0)
657 #if defined(CONFIG_IRQSOFF_TRACER) && \
658 defined(CONFIG_PREEMPT_TRACER)
660 static int preemptirqsoff_tracer_init(struct trace_array
*tr
)
662 trace_type
= TRACER_IRQS_OFF
| TRACER_PREEMPT_OFF
;
664 __irqsoff_tracer_init(tr
);
668 static struct tracer preemptirqsoff_tracer __read_mostly
=
670 .name
= "preemptirqsoff",
671 .init
= preemptirqsoff_tracer_init
,
672 .reset
= irqsoff_tracer_reset
,
673 .start
= irqsoff_tracer_start
,
674 .stop
= irqsoff_tracer_stop
,
676 .print_header
= irqsoff_print_header
,
677 .print_line
= irqsoff_print_line
,
678 .flags
= &tracer_flags
,
679 .set_flag
= irqsoff_set_flag
,
680 #ifdef CONFIG_FTRACE_SELFTEST
681 .selftest
= trace_selftest_startup_preemptirqsoff
,
683 .open
= irqsoff_trace_open
,
684 .close
= irqsoff_trace_close
,
688 # define register_preemptirqsoff(trace) register_tracer(&trace)
690 # define register_preemptirqsoff(trace) do { } while (0)
693 __init
static int init_irqsoff_tracer(void)
695 register_irqsoff(irqsoff_tracer
);
696 register_preemptoff(preemptoff_tracer
);
697 register_preemptirqsoff(preemptirqsoff_tracer
);
701 device_initcall(init_irqsoff_tracer
);